1. Field of the Invention
The present invention relates generally to a broadband communication system, and is more particularly related to scheduling of packet transmission and queue servicing within a satellite terminal.
2. Discussion of the Background
As society, in general, become increasingly reliant on communication networks to conduct a variety of activities, ranging from business transactions to personal entertainment, communication engineers continually face the challenges of optimizing use of network capacity and ensuring network availability to a diverse set of users with varying traffic requirements. Because capacity requirements of different users, for that matter of the same users, can fluctuate depending on time day and applications, the accuracy of traffic forecasts is diminished. Inaccurate forecasts can lead to negative effects, such as traffic congestion, slow response times, or even loss data. The maturity of electronic commerce and acceptance of the Internet as a daily tool by millions of users (this user base continues to grow) only intensify the need to develop techniques to streamline capacity usage. With the advances in processing power of desktop computers, the average user has grown accustomed to sophisticated multimedia applications, which place tremendous strain on network resources (e.g., switch capacity). Also, because the decrease in application response times is a direct result of the increased processor performance, the user has grown less tolerant of network delays, demanding comparable improvements in the network infrastructure. Therefore, efficient use of network capacity is imperative, particularly in systems where capacity needs to be managed carefully, such as a satellite network.
Satellite communications systems have emerged as an accessible and reliable network infrastructure that can support the exchange of voice, video, and data traffic. Conventionally, these satellite communications systems offer dedicated communication channels that relay or tunnel traffic without processing such traffic (i.e., “bent pipe”). That is, the system has no knowledge of what types of protocols are used or data that is contained within the packets. One drawback with these satellite communications systems is that they are highly inefficient with respect to bandwidth allocation. For example, if the satellite has excess transponder bandwidth at a particular time, this excess capacity cannot be temporality reallocated to another satellite terminal (ST). Another drawback is that the satellite cannot perform any processing on the received traffic; thus, key networking functions, such as flow control and congestion control, are not available. Yet another drawback concerns the inflexibility of the system to adapt dynamically to the traffic requirements of the STs. Given the bursty nature of Internet traffic, traffic emanating from the STs can vary greatly, thereby making it technically impractical to adjust the static channel assignments of the traditional bent pipe satellite systems.
Further, the STs, as an entry point into the satellite network, need to buffer large amounts of traffic. This buffering is conventionally accomplished using static queues. Given the diversity of traffic type, coupled with data flows of varying priorities, the use of static queues can result in wasted memory as well as unnecessary dropping of packets.
As a further challenge in the design of satellite networks, communication engineers need to minimize the effects of the inherent propagation delays of a satellite network. This design consideration is particularly relevant in the transmission of Internet traffic; notably, web traffic. In a typical web transaction, an end user enters a URL (Uniform Resource Locator) in a web browser that is resident with the host computer of the user. This host computer then requests the specified URL from a remote web server, which returns an HTML page that contains numerous embedded objects (i.e., web content) to the web browser.
The exchange of information between the web browser and the web server is governed by the HTTP (Hyper Text Transfer Protocol), which is an application level protocol. Upon receiving the HTML page, the web browser parses the page to retrieve each embedded object. The retrieval process often requires the establishment of separate communication sessions (e.g., TCP (Transmission Control Protocol) sessions) to the web server. That is, after an embedded object is received, the TCP session is torn down and another TCP session is established for the next object. Because HTTP utilizes a separate TCP connection for each transaction, the large number of transactions amplifies the network delay.
Based on the foregoing, there is a clear need for improved approaches for expediting web traffic by managing queues within the terminals of a satellite communications system.
There is also a need to enhance efficient utilization of the system capacity.
There is also a need to reduce response time associated with web traffic.
There is a further need to dynamically adapt to bandwidth requirements of the satellite terminals.
Based on the need to improve system efficiency, an approach for expediting web traffic in a satellite network is highly desirable.